Once Tom Cotton and Trump began promoting Chinese lab leak theories, liberals made it a sign of intelligence to reject the lab leak hypothesis out of hand.

There’s nothing else going on.

And already there’s a weird hedge that goes “So what if it turns out to be a lab leak? That’s not going to change our problems with vaccination rates and masking”

I think there’s a lot of skittishness around being seen as racist towards China, especially in the wake of Trump.

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This makes me think that basic Bayesian reasoning needs to be taught early. People argue as if the various factors (location, properties of previous new viruses,...) are all on different planes, so you just pick your favorite factor and ignore the others. But Bayes provides an obvious systematic way to combine different pieces of evidence, whether they point the same way or opposite ways. Most of the chances for non-lab crossover would occur elsewhere, so we can rule them out. In this case, with Wuhan having a little less than 1% of China's population and not being located in a viral hot spot, you'd take whatever odds you had based on other factors and multiple the Lab/Non-Lab odds ratio by ~100. That's not the ~infinite factor Jon Stewart seems to use but it's also not an irrelevant coincidence.

What would those other odds, not involving location, be? Some people say that there are so many more chances for nature to make new combinations that they are less than 1/100. Others say the lab was a good place for different strains to recombine, so they are more than 1/100. I don't know enough to comment on that. But including the location in the odds calculation is the easiest part to get very roughly right.

As you say, the name-calling adds nothing to the estimate!

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What's our excuse? Probably the social and psychological rewards of the sneering, poorly-thought-through Twitter dunk. The platform makes it so easy and satisfying to come up with a snarky response that sounds intellectually superior, and the culture that has grown up around the platform has normalized those kinds of responses so thoroughly, that even intelligent, well-informed people like Koerth yield to temptation. I've seen it in political as well as scientific disputes; I've seen the smartest people I know retweet dunks that are easily seen, on non-confirmation-biased reflection, to not really answer the argument they're dunking on. It's more evidence that Twitter culture is undermining both our cognition and our moral sense.

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We (liberals) let Trump break our brains and bring us down to his level.

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Thank you for focusing on the relevance of lab location. As a layperson, I've never understood why lab location was often dismissed. I see virologists stating that the chance of the pandemic having lab origins is "less than 1% for a lab leak of a natural isolate" and I wonder how on earth they calculate such a low figure. https://twitter.com/florian_krammer/status/1397880781675053057

Before the pandemic, both lab and natural scenarios in Wuhan would have been described as extremely unlikely. They're both very low probability events, but we know that one of them has since happened.

My back-of-an-envelope estimates: 1. For lab-leak accident, outbreak of 1,000 or more coronavirus infections from WIV might happen once in 500 to 50,000 years. 2. For natural spillover in Wuhan, outbreak of 1,000 or more coronavirus infections might happen once in 1,000 to 14,000 years. So both scenarios are very unlikely, but to me neither seems extremely unlikely compared to the other.

I looked at the lab risk assessment for the infectious disease labs at Boston University, which says 1,000+ infections of 1918 H1N1 flu might happen once in 10,000–1 million years. We could assume the same risk for the Wuhan labs and a SARS2-like virus. But if the WIV was doing coronavirus work in BSL2 and allegedly risky virus collecting then the risk of a coronavirus outbreak might be far greater than once in 10,000–1 million years. Could it be as high as once in 500 to 50,000 years? The Boston labs risk assessment summary is at: https://www.bu.edu/neidl/files/2014/07/Final-Supplementary-Risk-Assessment-7_2012-Readers-Guide.pdf

For natural spillover in Wuhan (once in 1,000 to 14,000 years): as a starting point I assumed five global outbreaks per century of 1,000+ infections of novel coronavirus. If I assume the chances of an outbreak in Wuhan are the same as everywhere else then the chances are once in 14,000 years. But coronavirus outbreaks are more likely in region adjacent to Wuhan, more likely to spread in big city, more likely detected in large modern city — so I might arbitrarily assign a lower range of once in 1,000 years. Apologies for the back-of-an-envelope approach although I’m not sure some virologists are doing anything more sophisticated when they calculate the chances of a lab-leak are less than 1%.

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Love the writing, Zeynep!

I would just say one criticism... I wish you wouldn't use the word "proof" at all in a conversation like this one. There's no proof to be had outside of math and deductive logic, and letting such binary terms into the conversation just lets people ignore you when you say "there's strong evidence of X" and they say "aha, but not proof!"

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I almost didn't read this article because I expected "more of the same," but I found it to be extremely informative: https://www.sciencemag.org/sites/default/files/Shi%20Zhengli%20Q%26A.pdf

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This is great and I particularly like the tweets from Maggie Koerth. It reminded me of a cartoon years ago in the Reader's Digest:

Caller to Highway department: "I want you to take down the Deer Crossing sign in front of my house.

Highway Department: "Why."

Caller: "I don't want the deer to cross there any more!"

We as a society used to be able to figure these things out...

Also I had not sen the comments on the Science Magazine article (https://www.sciencemag.org/sites/default/files/Shi%20Zhengli%20Q%26A.pdf) and I would like to have a link to the article.

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I just returned from the Chapel Hill Farmers Market before reading your post. Maybe I missed something, but did not see any bats for sale. Not even frozen bat dogs for Summer BBQ. So why is there a corona virus lab at UNC?

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It seems like there's as much political bias as confirmation bias.

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"Add the fact that the known first superspreader event (which we now know likely wasn’t where the virus originated from but just the first known amplifying event)."

What is meant by this qualification? I don't think it's been widely suggested that SARS-CoV-2 evolved or was created by recombination inside animals after they made it to the market, just that the market(s) is the probable location of the spillover event to humans. There is evidence of different virus lineages, some of which do not correspond with the Huanan market, but the temporality of the emergence is not fully clear- I think the notion of the spillover occurring elsewhere has not been established as "likely".

This remains the leading theory among the non-lab-leak-inclined scientific community- a population of infected animals, perhaps from a single farm, was distributed to multiple markets throughout Wuhan. See figure 1 here: https://virological.org/t/early-appearance-of-two-distinct-genomic-lineages-of-sars-cov-2-in-different-wuhan-wildlife-markets-suggests-sars-cov-2-has-a-natural-origin/691 Despite official denials and or cover-up, there has been some good research into the conditions and illegal contents of the wet markets: https://www.nature.com/articles/s41598-021-91470-2

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